Feature: "Give points": Possibility to limit points per option

[PhMemmel]

"Give points" is a nice distribution method. It would be even better (and open up to more use cases) if one could set a limit for each of the specified options.

So, for example, as student you have 10 points available to distribute among, let's say, 5 options, but you can at most give 3 points to a single option. With this option the teacher can enforce a real(!) distribution of the points while still allowing the students to weight their preferred options.

As far as I can tell it should be sufficient to restrict the number of points being able to distribute in the student's choice view, so it shouldn't be too big of a deal to implement this feature.